The way things have gone down in MSG for coachs in the JImmy Dolan era I'd say Riles saw the hand writing on the wall and left for an amazing opportunity with an owner willing to give him control, a massive contract and partial ownwership.
Maybe even more was respect.
If things were as we might suspect that both Donnie left after as he did not agree with the Melo trade and MDA demanding Melo be traded (not likly so in a way he forced his departure) then I kind of have respect for these guys.
Van Gundy flat out resigned and when guys took the money they got treated badly. Chaney and Wilkens were. Larry Brown was clearly frustrated, was not doing a good job, had no control over Marbury or his roster, and basically did everything he could to get fired. His roadside chats were clearly in violation to his contract.
HE so wanted to be fired. He wanted out. When was the last time you ever saw a coach leave like that. His agent joe glass as smart enough to put in his contract the clause that David Stern mediate any disputes. Glass knew what a little turd Dolan can be. Larry got 24mil in one year.
NOw Dolan got Woodson who has been been with his agent for years to fire him. Add woodson to a long list of coaches taking the money and compromising. Joe and Keith Glass did good for Woodson and DOlan makes him fire them. Not very cool. This is a great opportunity for woodson and Dolan knows he can control him. Forcing him to fire Glass is really low.
This is why Jax is not even being entertained. Knicks know he is old, successful and set in his ways and he will out smart Jimmy.
So in retrospect, I did not like the way Riles left but in hindsight he was the smart one.